There is increasing interest in using transcranial magnetic stimulation (TMS) as a treatment tool for various neurological and psychiatric disorders, including migraine, stroke, Parkinson's disease, dystonia, tinnitus, and depression. TMS is a noninvasive method that uses a weak transient magnetic field-induced current to stimulate regions of the brain. The magnetic pulse created by a magnetic field generator easily passes through the skull and induces small electrical currents to be generated that stimulate nerve cells in the targeted brain region. The United States Food and Drug Administration (FDA) has approved TMS as treatment for depression and migraine headaches. TMS is also used as a diagnostic tool for motor neuron diseases with spinal cord excitation.
In order to meet the need for improved TMS devices that provide for deeper organ and brain stimulation, new TMS tools will require higher pulse power and better focusing capabilities to combat field divergence caused by longer operational distances. Developing such focused TMS requires extensive testing before it can be applied to animals and then humans. Even after new and more focused TMS devices are developed, they will require regular calibration and maintenance to ensure precision in focusing and intensity. Accordingly, there is a need for measurement tools, such as sensor probes and systems employing sensor probes and phantoms (e.g., brain phantoms) to detect the TMS-induced field and current, their focality, intensity, and temporal and spatial characteristics.